I have a buddy with a early 2000's TJ that has an issue. I'll have more details this weekend,but it throws a check engine light and begins to miss anytime the tank goes below 1/4. Fill it back up and the light resets and the miss goes away. Been doing this for over a month now. I'll see him tomorrow and we're going to pull the codes then. Very strange problem. This really sounds like an emissions issue, like a plugged vent/return line or something. Idears?